Slag-tapping furnace having a floor with inclined edges



' 1935- R. M. HARDGROVE 1,986,666

SLAG TAPPING FURNACE HAVING A FLOOR WITH INCLINED EDGES Original FiledAug. 15, i950 2 Sheets-Sheet 1.

Jan. 1, 1935. I R. M. HARDGROVE 1,986,666

SLAG TAPPIN G FURNACE HAVING A FLOOR WITH INCLINED EDGES Original FiledAug. 13, 1930 2 Sheets-Sheet 2 ENTOR ATTORNEY;

Patented 1, 1935 UNITED STATES sue-ammo FURNACE HAVING A FLoo wrrnmcnmsn spurs Ralph Hardgrove, Westfleld, N. 1., ass ignor to FullerLehigh Company, Fullerton, Pa, a corporatlon of Delaware ApplicationAugust 13, 1930, Serial No. 475,011-

.. Renewed November 19, 1934.

8 Claims. (Cl. Rib-235) and is drawn off at intervals.

In furnaces of this character that have been used heretofore, troubleshave arisen when the slag is permitted to freeze and subsequently expandwhen again heated, with a result that the furnace walls are pushedoutwardly. This danger is sometimes caused because when the slag coolsand freezes, cracks form in it which subsequently receive more moltenslag that hardens therein, thus causing the slag slab to grow and expand.by successive heating and cooling.

By the present invention, the danger of the walls of the furnace beingforced outwardly is obviated by forming the floor in such a manner thatthe slag that collects upon the floor has thin edges that would becrushed without pushing the furnace walls out. The major portion of thefurnace floor is made substantially level but the edges thereof slopeupwardly or edges of the furnace floor merge into the lower portions ofwalls of the furnace along inclined surfaces. In this way, inclinedwater cooled surfaces are provided upon which the edges of the slab ofslag that may form in the furnace can slide.

The invention will be understood from the description in connection withthe accompanying drawings, in which Fig. 1 is a vertical section throughan illustrative embodiment of the invention; Fig. 2 is a section alongthe line 2-2 of Fig. 3, and Fig. 3 is asection along the line 3-'-3 ofFig. 1.

In the drawings, reference character 1 indicates a furnace that isprovided with one or more fuel burners 2 through one wall thereof.

- The front and rear walls of the furnace are provided with upwardlyextending water tubes 3 and the side walls of the furnace are providedwith upwardly extending water tubes 4. The lower ends of the tubes 3 and4extendinto horizontally disposed lower headers 6 and the upper ends ofthese tubes extend outwardly and into horizontally disposed headers 7.Recirculating tubes 8 are provided on the outside of the furnace betweenthe headers 6 and 7. Tubes 9 extend from the upper headers 'l to thesteam space of the water tube boiler that is located above the furnace1, only the lowest row of tubes 10 of this boiler being indicated onFig. .1 of the drawings.

' The lower headers 6 may be connected to the water space of the boilerby pipe connections in the usual manner.

A slag tap opening 11 is provided througha. wall of the furnace at aslightelevation above the floor of the furnace. The major portion of thefloor of the furnace is made up of refractory material 12 supported oncross supports 13.

The lower ends of the front and rear wall tubes" 3 and the lower ends ofthe water tubes 4 in thewall opposite the slag tap opening 11 are bentinwardly at their lower ends, as indicated at 14, to provide slopingsurfaces adjacent three of the edges of the floor of the furnace. Thefourth wall is substantially vertical where it contacts with the floor.(See Fig. 2.) i

It will thus be seen that the lower ends: of the water tubes 14 with therefractory covering thereon, provide inclined surfaces along the" edgesof the floor. As will be seen by referring to Figure 1, rigid supportsare provided at the ends of the water tube sections 14, and resilientsupports, here shown as spring supports, are provided intermediate theends of these tube sections.

Short auxiliary headers 6' are provided at two of the corners of thefurnace. A few of the tubes at these corners are bent first inwardly andthen outwardly as shown in Fig. 3 at 4' and are connected to theseheaders in such a manner as to prevent tubes in adjacent walls fromoverlapping or interferring with each other, as indicated in Figsl 2 and3 of the drawings. Tubes near these comers are bent successively togreater extents to provide satisfactory cooling means over the entirearea of the sloping corner portions of the furnace. The headers 6' areconnected to the water circulation system of the boiler in a mannersimilar to the connection of the headers 6.

During the operation of the furnace, the molten slag from the productsof combustion falls to the bottom of the furnace and forms a layer, asindicated at 15. Molten slag can be tapped out through the opening 11when desired. Since the inclined surfaces are water cooled, slag mayharden on these surfaces with thin edges, so that heating'and cooling ofthe slag which causes expansion thereof will not force the furnace wallsoutwardly as the slag can slide up the inclined surfaces along the edgesand the thin edges of the slag will be crushed without displacing thefurnace walls.

I claim:

1. In a furnace for burning a slag-forming fuel, a furnace bottomconstructed to sustain a pool of molten slag, said furnace bottomcomprising a central horizontally extending portion comprehending amajor portion of said bottom and edge tion and sloping upwardly fromsaid central portion, said edge portions being subjected to a greaterdegree of cooling than said central por-.

tion.

2. In a furnace for burning a slag-forming fuel, a furnace bottom'constructed to sustain a pool of molten slag, said furnace bottomcomprising a central horizontally extending portion comprehending amajor portion of said bottom and edge portions on at least three sidesof the central portion and sloping upwardly from said central portion,and cooling tubes in said edge portions, said edge portions beingsubjected to a greater degree jected to a greater degree of cooling thansaid.

central portion. a

4. In a furnace for burning a slag-forming fuel, vertically extending jside walls having cooling tubes, a furnace bottom comprising a central,

horizontally extending portion comprehending a major portion of saidbottom and inclined mar gin portions on at least three sides of thecentral portion, said horizontal portion extending into contact with avertical portion of one of said portions on at least three sides of thecentral per,

side walls and a slag tap opening in said side wall. 5. In a furnace forburning a slag-forming fuel,

upwardly extending side walls having cooling tubes, a furnace bottomcomprising a central horizontally extending portion comprehending amajor portion of said bottom, and inclined margin portions on at leastthree sides of the central portion, the lower ends of said side walltubes being bent and extended in heat transfer relationship to saidmargin portion.

6. In a furnace for burning a slag forming fuel, upwardly extending sidewalls comprising spaced water tubes and closure elements for the spaces,and a furnace bottom comprising a central horizontally extending portionconstructed to sustain a pool of molten slag and margin portions on atleast three sides of the central portion and inclined to said centralportion.

7. In a furnace for burning a slag forming fuel, upwardly extending sidewalls comprising spaced water tubes and closure elements for the spaces,and a furnace bottom comprising a central horizontally extending portionconstructed to sustain a pool of molten slag and margin portions on atleast three sides of the central portion and inclined to said centralportion and extending above the levelsof said pool.

8. In a furnace for burning a'slag forming fuel, upwardly extending sidewalls comprising spaced water tubes and closure elements for the spaces,

and a furnace bottom comprising a central horizontally extending portionconstructed to sustain a pool of molten slag and margin portions on atleast two adjacent sides of the central portion and inclined to saidcentral portion.

.RALPH M. HARDGROVE.

